Keppel married his wife, Mae Hubbard, in 1894. Four years later, the couple moved to Los Angeles where Dr. Keppel taught at the School of Los Angeles. After a few years of teaching, Dr. Keppel was elected Superintendent of L.A. County Schools.

Dr. Keppel was elected to the position of County Superintendent of Schools of Los Angeles County in 1902, 1906, and again in 1910. In 1914, the office came under Civil Service, and Keppel held it until his death. Leonitus Yeung, a relative of Keppel, resides as the vice president.